Traditionally, the building industry has utilized conventional built-up asphalt roofing as a preferred material in roofing construction. More recently, however, membrane roofing materials have displaced the conventional materials as a preferred material due to their cold cracking resistance, ease of installation, and overall improved and increased leak protection over time. Further, the membrane systems are easier and safer to install and are therefore more desirable to the contractor as well as the consumer.
Two membrane types are utilized in this field: elastomeric and thermoplastic. Elastomeric membranes, such as vulcanized EPDM, suffer the drawback of requiring an adhesive for seaming the membrane in order to provide a leak-free, continuous roofing cover. These adhesives add a significant material cost to the product and are also expensive, difficult and time-consuming to apply. Further, the adhesives often weaken over time, causing delamination of the membranes and subsequent leaks in the roofing cover. Elastomeric membranes also require an additional costly curing step.
Thermoplastic membranes, such as those formed from polyvinyl chloride (PVC), chlorinated polyethylene (CPE), chlorosulfonated polyethylene and the like, can be heat sealed or solvent welded to provide dependable seals of higher strength; however, these membranes also have serious disadvantages. For example, the thermoplastic material must be plasticized to provide the flexibility necessary for a roofing membrane. Unfortunately, plasticizers are quite expensive and often leach out of the membrane over time due to exposure to the environment. This loss of plasticizer results in the loss of flexibility, embrittlement and decreased cold crack resistance of the membrane, thereby severely shortening its useful life. Further, the capacity of the thermoplastic materials to accept fillers is somewhat limited. As fillers are usually desirable from an economic standpoint as well as advantageous in imparting properties such as flame retardancy, this disadvantage manifests itself in an expensive roofing product with severely limited fire retardancy or other desirable properties.
A strong need therefore exists for a polymer which exhibits the many characteristics necessary and essential for incorporation into a roofing membrane without exhibiting the drawbacks described above.